Emergent hybrid surgical approaches for non-dissecting ruptured Kommerell's aneurysm: a case report series

Abstract

Background

Kommerell’s aneurysm is a saccular or fusiform dilatation found in 3–8% of Kommerell’s diverticulum cases. A non-dissecting rupture rate of 6% has been reported. If ruptured, emergent surgical correction is usually granted. However, evidence regarding the optimal surgical approach in this acute setting is scarce. In this case report series, we aim to describe our experience managing type-1 non-dissecting ruptured Kommerell's aneurysm with hybrid emergent surgical approaches.

Cases presentation

From January 2005 to December 2020, three cases of type-1 non-dissecting ruptured Kommerell's aneurysm requiring emergent surgical repair were identified. The mean age was 66.67 ± 7.76 years, and 3/3 were male. The most common symptoms were atypical chest pain, dyspnoea, and headache (2/3). The mean aneurysm’s diameter was 63.67 ± 5.69 mm. Frozen Elephant Trunk was the preferred surgical approach (2/3). The Non-Frozen Elephant Trunk patient underwent a hybrid procedure consisting of a supra-aortic debranching and a zone-2 stent-graft deployment. We found a mean clamp time of 140 ± 60.75 min, cardiac arrest time of 51.33 ± 3.06 min, and a hospital stay of 13.67 ± 5.51 days. The most common complications were surgical-site infection and shock (2/3). Only one patient died (1/3).

Conclusion

Evidence of management for non-dissecting ruptured Kommerell's aneurysms is scarce. Additional, robust, and more extensive studies are required. The selection of the appropriate surgical approach is challenging, and each patient should be individualized. Frozen Elephant Trunk was feasible for patients requiring emergent surgical repair in our centre. However, other hybrid or open procedures can be performed.

Background

Kommerell's Diverticulum (KD) is a rare developmental abnormality of the aorta, associated in 20–60% of the cases with an aberrant subclavian artery (AScA) [1, 2]. It is currently known that KD results from an abnormal embryological remanent, secondary to a failed regression of the fourth primitive aortic arch [2]. According to its pathogenesis, KD can be classified into three different types: Type I KD is characterised by a KD secondary to an aberrant right subclavian artery (aRScA) in a left aortic arch; Type II KD is derived from an aberrant left subclavian artery (aLScA) with a concomitant right aortic arch; and finally, Type III KD is a diverticulum arising from the isthmus of the thoracic aorta without the presence of an ASCA [1, 3, 4].

A Kommerell's Aneurysm (KA) is defined as a fusiform or saccular (most frequent) dilatation of a KD, with a reported average size of 50.7 ± 7.1 mm [5]. They are extremely rare, as they can be found only in 3–8% of the KD [5,6,7]. Some authors have stated that a KA should be defined when the size of a KD is greater than 30 mm, since the risk of rupture (rKA) increases significantly, yet there is still no consensus [8, 9]. Histological studies highlight that KA requires a separate categorisation that distinguishes them from KD, as it has been demonstrated that medial cystic necrosis is present in the vessel wall of the KA [10]. It is hypothesised that this structural alteration relates to a higher frequency of fatal complications, such as distal embolisation, compression of adjacent structures, dissection, and rupture [7, 10].

KA tends to be asymptomatic. However, when symptoms are present, they could be attributed to complications. This is the case of dysphagia lusoria, a classic sign of an AScA, described as an impairment of swallowing due to oesophagal compression from an aberrant artery passing posterior to the oesophagus [1, 5]. Similarly, when the KA presents a dissection or rupture, the clinical presentation becomes alarming with signs or symptoms like rest dyspnoea, lancinating chest pain, or hemodynamic instability [2].

It has been described that KA has a concomitant dissection and rupture rate between 19 and 53% and a non-dissecting rupture rate range of 6–19% [2, 6]. Due to the implications of this condition, including death, emergent surgical repair is usually granted. Some elective surgical approaches have been proposed; however, evidence regarding the optimal emergent management for KA and rKA is mainly based on isolated case reports or a few KD cohorts, as shown in Table 1 [2, 5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22].

Table 1 Summary of reported Komerell's aneurysms reported in the literature

This article aims to describe the clinical characteristics and hybrid emergent surgical approaches for three patients with type-1 non-dissecting rKA in a single referral centre for cardiovascular surgery in Latin America.

Cases presentation

We present three patients diagnosed with type-1 non-dissecting rKA who underwent emergent hybrid surgical repair. Cases are summarised in Table 2.

Table 2 Characteristics of patients with type-1 non-dissecting rKA managed with an emergent hybrid approach presented in this article

Case number 1 (frozen elephant trunk (FET))

A 73-year-old male presented to the emergency room (ER) with intense pain in the left thoracoabdominal region accompanied by mucocutaneous pallor, diaphoresis, dizziness, weak pulses, and hypotension. Physical examination revealed peripheral cyanosis, tachypnoea, tachycardia, and decreased breath sounds in the left hemithorax. His previous history included an uncomplicated 23 mm KD incidentally discovered by an Angio-CT, hypertension, pulmonary emphysema, and hypertriglyceridemia. A chest X-ray was performed, showing a left pleural effusion. A presumptive diagnosis of rKA was established. An Angio-CT showed a 62 mm aneurysmatic diameter from the apex to the opposite wall of the aorta and a mural thrombus occupying 70% of its lumen without evidence of an intimal flap.

This patient underwent an emergent FET. During surgery, a rKA of approximately 70 × 70 mm was found, which caused a left haemothorax. Dissection of the rKA was performed, and antegrade cerebral perfusion was continuously given through both carotid arteries. FET technique was conducted, the end of the arch graft was inserted distally, the Dacron tube was then anastomosed to the descending aorta's origin, and a retrograde stent-graft was deployed in the descending aorta. The surgery required a 54-min cardiac arrest and a 70-min clamp period.

On the first postoperative day, the patient presented a right pneumothorax, requiring a closed thoracostomy. Later, he presented a left pneumothorax, hypoxic-ischemic encephalopathy, multiple runs of atrial fibrillation, and disseminated intravascular coagulation, complicated with a gram-negative septic shock. The patient died on the 11th postoperative day due to cardiorespiratory arrest secondary to sepsis.

Case number 2 (FET + ascending aortic reconstruction)

A 69-year-old male was referred to our institution for six months of interscapular severe pain associated with dyspnoea. An extra-institutional Angio-CT showed a fusiform dilation of the aortic root and a type 1 KA. The patient presented a headache at the examination, and a hypertensive crisis was diagnosed. Beta-blockers were initiated due to a high risk of acute aortic syndrome. An institutional Angio-CT revealed dilation of the ascending aorta of 45 mm, an aortic knob of 42 mm, and a type 1 rKA of 59 mm from the apex to the opposite wall of the aorta without evidence of an intimal flap.

The patient underwent an ascending aortic reconstruction + FET. Dissection of the ascending aorta, the aortic arch, including the neck vessels, as well as the first portion of the descending aorta, was conducted. A terminal-lateral anastomosis of the left carotid artery to a Dacron tube of 8 mm was performed. An antegrade endovascular straight stent-graft of 167 × 40 mm was deployed, and the distal part of the ascending aorta and aortic arch was replaced with a Dacron graft of 34 mm. A zone III distal anastomosis was created between the stent-graft and the Dacron. The supra-aortic branches were reimplanted as a single tissue patch with a termino-lateral anastomosis to the Dacron tube of 34 mm. Aortic clamp time lasted 179 min, circulatory arrest 52 min, and extracorporeal circulation 275 min.

The patient presented hyperactive delirium and postoperative mediastinitis, which were successfully treated. After full recovery, the patient was discharged after ten days with no further complications. Five years later, the patient was admitted due to respiratory symptoms. A CT scan showed pneumonia, the KA was excluded, and a successful arch reconstruction was visible (Fig. 1).

Fig. 1

Case 1, non-gated postoperative chest CT at five years follow-up. A, B, and D Coronal images show appropriate positioning and patency of the thoracic graft with no further dilation or other complications (yellow arrows on C and D). A correct re-implantation of the supra-aortic trunks is also visualised (green arrows on A and B). A thrombosed aneurysmal sac is also evidenced (blue arrows on C and D). D Note the predominantly bi-basal opacities in the context of community-acquired pneumonia

Case number 3 (supra-aortic debranching + TEVAR)

A 58-year-old male was referred to our institution with an extra-institutional chest X-Ray that revealed a left pleural effusion and mediastinal enlargement and an Angio-CT that showed a rKA of 70 mm from the apex to the opposite wall of the aorta. The patient had a previous history of hypertension. He presented to the ER with a sudden onset of intense oppressive chest pain radiating to the left arm, accompanied by severe shortness of breath and general malaise. Physical examination revealed a hypotensive, tachycardic, and tachypnoeic patient, and initial arterial blood gases showed hyperlactatemia.

The patient immediately underwent surgery for supra-aortic debranching + TEVAR. Selective anterograde cerebral perfusion was given through the left carotid artery. A retrograde stent-graft was deployed in zone-2. A KA of approximately 60 × 80 mm was dissected. Subsequently, the neck vessels were anastomosed to a 24 mm Dacron tube. An 8 mm Dacron was anastomosed to the aLScA and proximally to the ascending aorta (Fig. 2). After 171 min, the aortic clamp was removed, and the cardiac arrest was reversed after 48 min.

Fig. 2

Intraoperative image of the rKA open stage of the hybrid repair. The complete aortic arch replacement with no acute bleeding and correct positioning is shown (yellow arrow). The reconstruction and reimplantation of the supra-aortic vessels can be observed (green arrow)

The patient presented multiple complications during hospitalisation, including a vasoplegic hypovolemic shock, delirium, bacteraemia, and drop foot, all of which were appropriately managed without any long-term consequences. The patient was discharged 20 days after admission without any sequelae. After two years of follow-up and an Angio-CT showed an adequate evolution (Fig. 3).

Fig. 3

A Axial and B coronal CT angiography images showing the anastomosis site of the reimplanted left subclavian artery and the aortic arch (white arrow) as well as the anastomosis between the distal ascending aorta and the Dacron tube (yellow arrow)

Discussion and conclusions

KD's management has different approaches depending on the patient's comorbidities, clinical presentation, anatomy, and the surgeon's expertise and personal preferences [1, 2, 23]. Some authors recommend surgical correction only in symptomatic patients since this population has been found to have an accelerated growth rate and a higher risk of rupture [1, 2]. It is also proposed to intervene in all patients with a KD diameter > 30 mm at the base of the KD or a distance from the apex of the KD to the opposite wall of the aorta of > 50 mm [1, 8].

After three years of follow-up, elective open and endovascular approaches demonstrated similar cumulative mortality; 16 and 18.2%, respectively. In this context, endovascular approaches may be an attractive alternative as they are associated with a lower incidence of postoperative pneumonia, shorter duration of invasive mechanical ventilation and shorter hospital-stay length. [2, 10, 24,25,26,27]. Evidence regarding hybrid approaches such as FET or thoracic endovascular aortic repair (TEVAR) plus supra-aortic debranching has been increasing recently, showing similar results in the short term compared to the endovascular management [18, 19, 23,24,25,26, 28, 29].

A systematic review of the literature compared the three approaches for KD. All are relatively safe and effective, showing no differences in outcomes, including 30-day mortality or stroke. The only significant difference was in the group of patients that underwent endovascular interventions, showing a higher number of re-interventions, mainly due to the appearance of endoleaks (11.6%) [30]. Each approach will be discussed in more detail in the following paragraphs, and their advantages and disadvantages are summarised in Table 3 [23, 27, 28, 30,31,32,33,34,35,36].

Table 3 Summary of the advantages and disadvantages of the different approaches and techniques for the correction of KD and KA

Given its low incidence, the evidence regarding the management of rKA needs more robust and extensive studies reporting long-term outcomes. There is even lower evidence about the most appropriate surgical approach for type-1 non-dissecting rKA. As a result, in the following section, we will describe the existing data about the different surgical approaches for all types of rKA.

Hybrid approach

Hybrid approaches are generally preferred as they are less morbid, avoid thoracotomy, and permit a posterior TEVAR if necessary. [28, 31]. Several techniques have been described. The most commonly performed are the FET and TEVAR + Supra-aortic debranching [30].

The TEVAR + supra-aortic debranching technique offers the possibility of performing a primary repair or alternative correction (embolization) of the AScA [31]. However, it does not solve the problem of the proximal landing zone and has been associated with complications such as branch occlusion, endoleaks, and stent-graft migration [31, 33]. One of its main advantages is that it can be performed in one or two stages, depending on the patient's surgical risk and general clinical condition [20].

The FET technique solves the issue of a limited proximal landing zone by performing a blood thigh proximal fixation and, therefore, decreases the risk of Type I and Type III endoleaks or stent-graft migration. This is achieved by approaching the arch through a sternotomy and suturing the stent-graft directly into the aortic arch. In addition, this approach allows direct access to the heart and the ligamentum arteriosum, which is highly useful when approaching patients with complex anatomies [28, 33]. It also decreases the potential risk of aortic rupture between procedures associated with the traditional elephant trunk, as it is a 1-staged procedure. [28, 32, 34]. The main disadvantage is that it requires longer cardiac arrest times, increasing the risk of cardiac, brain, and visceral ischemia [32, 33]. Likewise, it has been described that if the distal stent-graft is deployed below T7-T8 vertebral levels, the risk of spinal cord ischemia increases [32].

Ben Abdallah et al. [15] presented a 74-year-old male patient with a 81 mm contained rKA, who underwent a one-stage hybrid procedure. Initially, a TEVAR was performed associated with cervical debranching of the aLSA; then, a left carotid endarterectomy. This decision was related to the risk of haemorrhagic stroke due to cardiac arrest. Although the primary procedure was successful, the patient underwent two secondary procedures, one for vertebrobasilar insufficiency and the other for a right cervical lymphocele. After a four-month follow-up, the patient had fully recovered.

Another case report by Singh et al. [17] reported a 62‐year‐old African American male patient with acute onset tearing chest pain. An angio-CT identified a dissecting 40 mm Type I rKA with an intramural hematoma. The patient underwent a total arch replacement consisting of a right carotid-subclavian bypass, followed by open debranching of the bilateral carotid arteries and a zone II arch replacement with proximal intrathoracic ligation of aRSA and LSCA. Posteriorly, the patient underwent a FET. A retrograde TEVAR due to a type of IA endoleak was conducted in a second intervention. The patient presented a right lacunar infarct requiring a tracheostomy and percutaneous gastrostomy. After discharge, the patient persisted with mild residual left‐sided weakness.

Sica et al. [20] reported the case of a 74-year-old male patient with a saccular 70 mm Type II rKA associated with an anomalous course of the left brachiocephalic vein, which coursed posteriorly to the ascending aorta, and joined the right brachiocephalic vein to form the superior vena cava. Besides, a hematoma of the descending aorta was found, forming an extrapleural hematoma. The patient underwent a TEVAR, and a vascular plug was placed into the first segment of the aLSA. Twenty hours later, in a second surgical time, a left carotid-axillary bypass was performed. The length of hospital stay was 15 days. The patient presented transient tetraplegia. Nevertheless, at a 2-year follow-up, there were no residual or additional complications.

The evidence described above is related to our cases. We consider this approach promising for rKA as it allows an individualized approach for each patient. Furthermore, it is feasible in emergent situations as it is an effective, less invasive alternative compared to open approaches and does not require extensive planning or more specific resources like total endovascular approaches.

Open approaches

Historically, this has been the mainstay approach for rKA, as shown in a review by Cinà et al. [8]. Besides providing good access to the affected structures, it allows symptomatic relief and treatment of any related congenital or acquired cardiac abnormalities. It is particularly valuable for patients with complex anatomical variations as it allows complete visualization of the heart and great vessels, and in patients at high risk of stroke as it provides the possibility of securing brain perfusion. [23, 30, 36]. Nevertheless, it is highly invasive and morbid, requiring extensive surgical incision and multiple accesses strategies.

A study by Ikeno et al. [2] presented two patients with rKA who underwent emergent open surgery. The first patient included was a 77-year-old male with a dissecting rKA of 50.9 mm in diameter, who underwent an extensive aortic repair with selective anterograde cerebral perfusion. The authors reported no long-term postoperative complications in this patient. The second patient included was an 89-year-old male patient that presented a non-dissecting rKA with a diameter of 52 mm and underwent a total aortic arch replacement with selective antegrade cerebral perfusion. In-hospital mortality secondary to pneumonia was reported.

A case report by Kaki et al. [11] described a 73-year-old female patient with a 35 mm Type II rKA. An initial open proximal anastomosis was performed with a branched vascular graft. Then, the vascular graft was clamped, the aLSA was reconstructed, and reperfusion of the upper body was started through the rKA distal anastomosis. The patient presented pneumonia, which was treated adequately. The total hospital stay length was 70 days.

Endovascular approach

The evidence regarding the utility of this approach for rKA is null. This may be due to the requirement of extensive surgical planning since, for the complete treatment of the pathology, it is necessary to use chimney and periscope techniques that require surgeon-modified and custom-made thoracic endografts. Additionally, favourable anatomy with no evidence of anomalous supra-aortic branches or alterations of the descending aorta and a healthy landing zone with no calcifications, dilatations, or thrombi is required.

However, in centres with adequate experience and resources available, a total endovascular approach could be considered for select emergent cases, such as patients with contained rKA or those at high risk of surgical complications., However, its major role is in preventing rupture or dissection of KA. A proximal anterograde chimney technique with a retrograde approach to improving the proximal seal and a concomitant periscope technique should be performed to maintain the AScA patency [35, 36].

TEVAR with or without embolization of the AScA have also been described, but with complications such as arm claudication, predisposition to spinal ischemia, subclavian steal syndrome, and vertebrobasilar insufficiency [35]. Vascular plugs or coil embolization can prevent retrograde blood flow, and sometimes it has been related to decompression of the aneurysmal sac [31]. Additionally, given the sharply-curved distal arch (small radius curvature) when a KA is present, there is a predisposition to kinking, collapse of the thoracic endograft, or aortic wall injury by stent fractures [31, 35]; In this setting, some authors suggest the use of bare metal stents to decrease the risk of mechanical complications associated with stent fracture [36]. These techniques may be suitable in patients with a Type III KA.

It should be noted that endovascular techniques are contraindicated in the presence of compressive symptoms as the failure of clinical symptoms to improve has been described in the setting of complete vascular rings or if aneurysmal size reduction is not successful [23, 28, 30, 34].

In conclusion, technique selection must be individualised for each patient, depending on various factors such as the availability of resources, the patient's status (symptoms, hemodynamic condition, surgical risk, comorbidities), the different anatomical variations that may be present, and the surgeon's ability and preference. In our experience, FET can be a feasible procedure for patients with rKA requiring emergent surgical repair. However, other hybrid or open procedures could also be successfully performed. More robust studies are required to assess each approach's quality and long-term results to establish the most effective and safe for rKA.